"In a previous item, we described how the AmigaOS4.0 memory system works in terms of managing memory allocations from the top. However, there is more to allocating memory than that. The object caches of course work on memory that has already been mapped into the virtual memory space. But both the virtual address ranges, as well as the physical memory has to come from a source, too."

Yes, it is also targeting desktop computing, but that is not what will bring the bread and butter for the developers.
I think the closest to desktop computing we will see in the immediate future besides hobbyists is minimalistic terminals with clients for remote access - for instance there is an excellent RDesktop port for OS4.

But what percentages can be won from desktop adoption in the short run will hardly pay for continued development. Finding OEMs that are interested in solutions like this and selling components where it makes sense (such as the licensing of 3D driver technology which was done in March this year) is most likely what will keep development going, till the OS reaches a level where it can comfortably accomodate the average computer user.